Development Of Integrated Process For The Production Of Botanical Fungicides,Plant Growth Regulator And Ethanol From Rice Straw

As a renewable resource,rice straw has been widely used in biorefinery.Due to its high contents in carbon and nitrogen,rice straw can be used as the raw material of bioenergy and widely applied in the development of society.However,the conversion of straw waste into bioenergy could release some bioactive substances.These substances tend to exhibit high biological activity and some may inhibit the biorefinery process.The potential value of these active substances remains to be exploited.The essay discussed the effects of polyphenols,polysaccharides and other bioactive substances released from rice straw on plant pathogen infection and plant growth regulation,and studied the saccharification and fermentation of residues after the extraction of bioactive substances from straw.The data obtained are as follows:1)The rice straw was mixed with 2%Na OH(1:10)at 121? for 20 min and straw phenolic acid(PAs)was extracted by ethyl acetate.The effect of straw phenolic acid on the growth of Botrytis cinerea was investigated.The HPLC assay showed that the PAs consisted mainly of p-coumalic acid(CA)and ferulic acid(FA).The PAs exhibited strong inhibitory effect on mycelial development and spore generation,and at 0.2 g/L PAs,mycelial growth and spore generation decreased by 86.18% and 69.10%,respectively.Confocal microscopic image demonstrated that PAs changed the biological morphology of B.cinerea.Under PAs stress,hyphae tend to clump rather than stretch out,which may be the major inhibitory effect of PAs on mycelial growth.To confirm the feasibility of PAs as a fungicide,the effect of PAs on alleviating infection of tomato leaves by B.cinerea was investigated.The addition of PAs could increase the activities of PAL and PPO,and lower the activities of POD and CAT in the infected leaves,indicating that PAs increase the tolerance towards B.cinerea by reducing the oxidative stress of tomato leaves.Chlorophyll fluorescence imaging indicated that PAs could alleviate the destruction effects of B.cinerea on photosynthetic performance of leaves.2)The 15 ball-milling straw was mixed with deionized water(1:10)at 60? for 1h and released HS(Humic substances).The research first conducted component analysis on HS,and then performed component separation on it.The effects of different components on germination of tomato,cucumber and rape were discussed.It was found that polysaccharides and polyphenols had good effects on seedling germination,especially on seedling growth and dry weight.The research also explored the effects of polysaccharides and polyphenols on tomato plant growth,and found that they promoted plant height by 30.04% and 18.66%,leaf number by 13.88% and 20.85%,respectively,and antioxidant capacity in plant leaves was also improved.SOD was increased by 89.23%,POD by 84.78%,and CAT by 77.64%.3)The residue of HS extraction was applied into the production of ethanol,and discussed the influence of bioactive material extraction on saccharification and ethanol fermentation.The experimental results showed that compared with the traditional process(without HS extraction process),the saccharification efficiency was reduced by 7.71%,which was due to the loss of some polysaccharides in the HS production process.However,the final ethanol fermentation efficiency was improved.Compared with the untreated straw,the ethanol concentration and yield increased by 29.39% and 52.83% when the treated straw residue was used as the raw material for fermentation for 48 h.Because HS has a strong inhibitory effect on yeast growth,HS extraction can reduce the inhibitory substances in the fermentation broth,thus improving the efficiency of ethanol fermentation.This study was mainly committed to the development and utilization of polyphenols and polysaccharides secreted from straw biomass as plant-derived fungicides and plant-derived growth regulators.Moreover,the complex structure and polyphenol content in the residue were reduced,and the residue was used for saccharification and fermentation.This kind of botanical fungicides-plant growth regulator-ethanol fermentation integrated process can improve straw utilization rate,enhance ethanol conversion efficiency and provide innovative thoughts on rice straw resource.